Characterization of stochastic noise and post-irradiation density growth for reflective-type radiochromic film in therapeutic photon beam dosimetry

Previous work has shown that post-irradiation annealing, at temperatures near 1100°C, produces resolvable dislocation loops in tungsten irradiated to fast (E > 1 MeV) neutron fluences of about 4 x 1019 n/cm2 or greater. To crystallographically characterize these loops, tilting experiments were carried out in the electron microscope on a polycrystalline specimen which had been irradiated to 1.5 × 1021 n/cm2 at reactor ambient temperature (∼ 70°C), and subseouently annealed for 315 hours at 1100°C. This treatment produced large loops averaging 1000 Å in diameter, as shown in the micrographs of Fig. 1. The orientation of this grain was near (001), and tilting was carried out about axes near [100], [10] and [110].

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Optical characterization of a radiochromic film by total reflectance and transmittance measurements

Medical Physics ◽

10.1118/1.1764701 ◽

2004 ◽

Vol 31 (7) ◽

pp. 2147-2154 ◽

Cited By ~ 11

Author(s):

Franco Fusi ◽

Luca Mercatelli ◽

Giacomo Marconi ◽

Giacomo Cuttone ◽

Giovanni Romano

Keyword(s):

Optical Characterization ◽

Radiochromic Film ◽

Total Reflectance

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Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality

Journal of Radiotherapy in Practice ◽

10.1017/s1460396918000687 ◽

2018 ◽

Vol 18 (03) ◽

pp. 280-284 ◽

Cited By ~ 4

Author(s):

Mohamed Bencheikh ◽

Abdelmajid Maghnouj ◽

Jaouad Tajmouati

Keyword(s):

Exponential Decay ◽

Target Volume ◽

Photon Beam ◽

Field Size ◽

Photon Beams ◽

Energy Agency ◽

Percentage Depth Dose ◽

Depth Dose ◽

Beam Dosimetry

AbstractAimThe purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality.Materials and methodsFor the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations.Results and discussionThe 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions.ConclusionThe dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.

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